Fast repair of deoxythymidine radical anions by two polyphenols: rutin and quercetin.

The effects of rutin and quercetin on the repair of the deoxythemindine radical anion (dT*) were studied using the technique of pulse radiolysis. The radical anion of dT was formed by the reaction of hydrated electron with dT. After pulse irradiation of nitrogen-saturated aqueous solutions containing dT, 0.2M t-BuOH and either rutin or quercetin, the initially formed dT*(-), detected spectrophotometrically, rapidly decayed with the concurrent formation of the radical anion of rutin or quercetin. The results indicated that dT*(-) can be rapidly repaired by rutin or quercetin. The rate constants of the repair reactions were determined to be 3.1 and 4.1 x 10(9)M(-1)s(-1) for rutin and quercetin, respectively. With substitution by glycosyl groups at C(3)-OH bond being neighbor to C(4) keto group, which is the active site for electron transfer, rutin has a lower repair reaction rate constant toward dT*(-) than quercetin. Together with findings from our previous studies, the present results demonstrated that nonenzymatic fast repair may be a universal form of repair involving phenolic antioxidants.